Granite countertop span needs support

DEAR TIM: My husband and I are just about at the end of an arduous and stressful kitchen remodel. Originally, in the planning phase, the general contractor said we didn’t need a support under a long peninsula countertop made with solid granite. Now the field construction manager feels very uncomfortable with the 50 inches of unsupported granite that spans between a cabinet and two decorative posts at the end of the peninsula. I like the clean look we have now with no supports. How would you solve this problem? – Linda H., Broomfield, Colo.

DEAR LINDA: We can solve your conundrum and keep everyone happy. But, as with most things, there’s going to have to be some compromise.

My college degree happens to be in geology, and granite is by far my favorite rock. I love everything about it, most of all the varied colors and crystals you can get. Believe it or not, my house is built on what’s considered to be the most attractive rock in all of New England, the Meredith Porphyritic Granite.

This stunning bedrock contains massive white feldspar crystals, some the size of giant cocktail shrimp, in a fine-grained black matrix. I have a huge block of this ledge exposed right next to my driveway.

I’ve had discussions like yours with quite a few customers that focused on form vs. function. That’s what we’re dealing with here. You mentioned that you’re attracted to the clean look of the current top with nothing underneath it. I respect that, but function is paramount in my mind.

My decades of job site experience cause me to look at situations like this differently. The vision I have is not unlike “A Christmas Carol,” in which Scrooge gets to look into the future.

In your future, I see a party at your house attended by quite a few teenagers, and one of them decides to sit on the countertop at the center of the unsupported span. I also see a painter standing on the countertop because he’s too lazy to move his ladder. Both visions end up with large chunks of granite on your gorgeous hardwood kitchen floor.

You probably think that granite is extremely strong – after all, it’s granite. Just about every stone product, including artificial stone such as concrete, is very strong in compression. This means if it is squeezed, thousands of pounds of force per square inch are required to cause a crack.

While your granite has great compressive strength, it’s very weak in tension. Tension is the opposite of compression. A stone is subjected to tension when it’s stretched. If you were to load the center of your granite peninsula countertop right now with a given amount of weight, the bottom of the granite starts to stretch or pull apart.

While I can’t say exactly what the tensile strength of your granite top is for its current thickness, it’s usually only 10 percent of what it exhibits in compression. The bottom line is that your granite top could crack and tumble to the kitchen floor with as little as 100 or 150 pounds loaded at the center of the 50-inch span.

I often talked to customers about cost. What would it cost to replace a broken countertop? Would it be possible a year or two down the road to get a matching piece of granite? Remember, granite is a natural product, and the colors, crystal structure and so forth can vary in the quarry. You may not even be able to get a matching slab six months from now, much less two years from now.

I feel you need to install a support that runs down the center of the peninsula. It can be very narrow and provide the necessary bracing to prevent failure when someone loads the center of the top.

Here are a few options that popped into my mind. I’m sure that a kitchen designer might have some additional ideas swirling about in her/his head.

The simplest idea is to have a custom panel made that’s about an inch or so thick that matches the look of the two end posts at the corners of the peninsula. This would provide you with the maximum space under the top in case you thought about putting low stools at the counter.

If you’re willing to give up a little more legroom, you can have a thin cabinet made that has glass doors on both sides. I see in the photo you provided that the cabinet facing your front door has glass doors so that you can see what’s in the cabinet. You might display decorative items in this narrow cabinet under the granite. With glass on both sides you’ll be able to see through it, which would help preserve that clean look you like.

You might also have a narrow, open bookcase installed under the granite. Many books are just 6 or 8 inches deep, and this would not take up too much space. The bookcase wouldn’t have to be packed full of cookbooks, and if you do this, once again, there will be open space that helps satisfy your desire to keep the look sleek and simple.

You’ll not lose a moment of sleep once you have support under that granite. My vote, in case it counts, is to go with the thin cabinet with the glass doors. I’d put a bunch of my colorful granite rock samples in it!

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